Pterocarpus Macrocarpus Kurz
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Pterocarpus macrocarpus Kurz JOHN K. FRANCIS International Institute of Tropical Forestry, USDA Forest Service FABACEAE (BEAN FAMILY) Lingoum macrocarpum (Kurz) O. Ktze., Lingoum cambodianum Pierre, Lingoum glaucinum Pierre, Lingoum gracile Pierre, Lingoum oblongum Pierre, Lingoum parvifolium Pierre, Lingoum pedatum Pierre, Pterocarpus cambodianus Pierre var. calcicolus Craib Burma padauk, pradu, terocarpus Pterocarpus macrocarpus grows naturally throughout the Pterocarpus macrocarpus produces a timber with heart- greater part of Burma, northern Thailand, Kampuchea, and wood that varies from golden brown to brick red. It is compa- into Vietnam (Carrapiett 1960, Hundley 1956, Suvarnasuddi rable in workability to inferior quality teak. Used for furniture, 1950). It is an associate with Tectona grandis L.f. in moist to cabinetry, flooring, ship timbers, cart wheels, tool handles, house dry deciduous forests. framing, and posts (Chudnoff 1984, Hundley 1956, Rendle Pterocarpus macrocarpus is a large tree with a medium 1970), the wood is very resistant to termites and rot (Carrapi- growth rate. It develops long and relatively straight boles in ett 1960). A visually pleasing tree, P. macrocarpus is planted closed forest, but as an open-grown tree, tends to have short throughout the moist tropics as an ornamental and shade tree boles and spreading crowns. In their native range, these trees (Rojo 1972). However, older trees have large roots that run seldom exceed 30 m in height and 70 cm d.b.h. (Hundley along the surface of wet or clayey soil and have a high propen- 1956). However, as ornamentals, P. macrocarpus trees may sity to damage sidewalks and curbs (Francis and others 1996). reach impressive sizes. A tree approximately 64 years old in Flowering and fruiting usually begins in open-grown Puerto Rico measured 39 m in height and 1.7 m d.b.h. (Fran- trees between 5 and 10 years of age. The sweet-scented yellow P cis 1989c). Suitable soils include sandy loams through clays flowers are produced copiously in panicles and racemes. Indi- with pH ranging from neutral to very strongly acid. Rainfall vidual flowers measure about 1.6 cm across. They are pollinat- throughout the native range varies from about 1000 to 2000 ed by honey bees and other insects. The fruit of P. macrocarpus mm per year (Kermode and others 1975). The tree grows from is a lenticular-shaped pod with a flat wing that circles its edge. near sea level to 670 m elevation. Mean monthly temperatures These pods have a diameter of 4.5 to 7.5 cm. Large trees may are fairly uniform at about 24 °C. (Francis 1989c). Because it produce one to several quintals of pods annually. grows somewhat more slowly than its fiercely competitive At maturity, the pods dry and turn from greenish yellow associates, P. macrocarpus usually must survive years of sup- to light brown and can be clipped from low-growing trees with pression as a sapling or pole until disturbance creates a canopy pruning poles. Fruits mature about 6 months after flowering gap through which it can grow. As a result, the species makes and fall off the trees gradually over several months. Because up only a small percentage of the canopy trees in its native the fruits and their seeds do not deteriorate for several months habitat (Hundley 1956). after falling, they may be collected efficiently from the ground Pterocarpus macrocarpus is closely related to P. indicus Willd., when most of the crop has fallen. The pods are air-dried and and it is difficult to distinguish between the two species by leaf stored in plastic bags with or without refrigeration. A sample and flower morphology alone (Rojo 1977). The fruits of P. macro- of air-dried pods of P. macrocarpus collected in Puerto Rico carpus are usually larger, darker, and have more pronounced cen- yielded 1,067 pods per kg (Francis 1989c) and an average of tral veins than P. indicus, but where the native ranges merge and 2.6 seeds per pod (Francis 1989c). Air-dried seeds in their pods at the extremes of natural seed variation, differentiating be- will still germinate after 1 year of storage at room temperature. tween the species is difficult. No hybrids have been reported. The pods are tough and the seeds are fragile, making extrac- Part II—Species Descriptions • Pterocarpus macrocarpus Kurz 673 tion impossible mechanically and difficult by hand. Shelled pods about 1 to 2 weeks after planting. The remaining seeds seeds average 11,500 per kg (Francis and Rodríguez 1993). continue to germinate for several weeks. Using seeds in the The seeds are usually planted in the pods without any pods sometimes requires thinning the plants soon after emer- pretreatment. Germination is epigeous. In a comparison gence. When true leaves develop, seedlings are transplanted study, shelled seeds germinated in 5 days, with 70-percent ger- into 1- to 2-L nursery bags filled with potting mixture. After mination within 2 weeks. Unshelled seeds began germination growing under light shade for a few months, the seedlings in 11 days with 64 seedlings per 100 pods germinating within reach about 0.5 m in height and are ready to outplant (Francis 2 months. In a test in Burma, shelled seeds gave 80- to 90-per- 1989). In Burma, seedlings in plantations grew from 0.6 to 1.2 cent germination. Moreover, seeds from pods that had lain on m the first year and added another 1.2 to 2.1 m in the second the ground for 1 year germinated better than new pods col- (Hundley 1956). In Puerto Rico, 30 planted trees in a small lected from the tree (Hundley 1956). The best temperature forest plantation that was situated on clay soil over porous regime seems to be about 30 °C day and 25 °C night (Liengsiri limestone averaged 1.3 m in height 14 months after outplanti- and Hellum 1988). ng (Francis 1989c). Seedlings intended for ornamental use are Lightly covered with a high-organic potting mix in ger- often grown in 12- to 20-L plastic pots until they reach 2 to 3 mination trays or beds, the seeds begin to grow through the m in height before outplanting. P 674 Part II—Species Descriptions • Pterocarpus macrocarpus Kurz P Part II—Species Descriptions • Pterocarpus macrocarpus Kurz 675.